Slow Running Queries after IMPDP

Question

Hi Xperts
I have been doing table data and sequences restore every day, because the user ask for it.
The user works with the Data Base to test some applications and at the end of the day
I do table data restore to return the information to some point.
I truncate every table, disable Constraints, disable Triggers and then I do and IMPDP
of table data and sequences, then I enable Triggers, Constraints and at the
end I execute statistics. This procedure is Only for one Schema.
The problem is that some days the queries work fine, but, others days the queries work slowly.
The procedure is the same every day.
This is a Test Data Base: 11g R2, ASM under Oracle Linux 5.8 64bits
Any advice ? why do some days the queries work properly ? others days work Slowly ?
I execute statistics like this:
exec dbms_stats.gather_schema_stats('MYSCHEMA');
exec dbms_stats.gather_database_stats;
exec dbms_stats.gather_dictionary_stats;
IMPDP:
impdp system/oracle1 FULL=NO SCHEMAS=MYSCHEMA CONTENT=DATA_ONLY directory=IMPDP_DIR dumpfile=Full_MYSCHEMA.dmp logfile=IMPDP_Full_MYSCHEMA.log
impdp system/oracle1 FULL=NO SCHEMAS=MYSCHEMA CONTENT=METADATA_ONLY INCLUDE=SEQUENCE directory=IMPDP_DIR dumpfile=Full_MYSCHEMA.dmp logfile=IMPDP_Full_MYSCHEMAseq.log
Thank you in advance
J.A.

Answer 1

The problem could be statistics. A simple fix would be to lock the statistics at the end of a day when performance is OK, and don't try to gather them again.
By the way, a much better way to do this (better in terms of work for you and repeatable behaviour for your client) would be to enable database flashback for this sort of thing rather than repeatedly importing. Flashback requires Enterprise Edition licences.
John Watson
Oracle Certified Master DBA
http://skillbuilders.com